This is an interactive model for thinking training. Imported beech wood+environmentally friendly water-based paint, no sharp corners. Cactus branches and rotatable leaves can be assembled into various balanced shapes. The bending angle of cactus varies depending on the position of the leaves. Sort by ABAB or AABB to cultivate pattern thinking. Principle of photoelectric sensor (intelligent version)/Principle of center of gravity and lever (wooden version). Record the height and tilt angle of different shapes, and draw a simple bar chart. Several children can use 10 wooden blocks together to assemble the tallest but still standing cactus. Can you challenge the stability of the plug-in structure - who built the cactus to stand the most stably?